To identify cultured human tumor lines on the basis of polymorphic and tissue specific enzyme patterns, we will analyze cultured human cell lines, and malignant and corresponding normal patient tissues, and tumors of human malignant cells produced in the athymic nude mouse. Methods will include electrophoresis using starch gels and Cellogel, isoelectric focusing in polyacrylamide gels, and spectrophotometric assays. The vast collection of cultured human tumor cell lines and tumor lines available in this laboratory will be the object of study. It is the intention to examine whether the lines are bona fide representatives of the tumors and the types of tumors they are claimed to be.